Need some help on my game

So at the moment I'm making a traffic game (where there is a 4 way cross road and you have to control one of the sides with a set of traffic lights).

I'm stuck on 2 things:

First one is spawning. I need to spawn a car at random 1-3 seconds and also spawn different types of cars (as I have different coloured cars and I don't want them to be the same).

Second thing is stopping. once the first car is stopped, the car behind goes ontop. I know I could put collide but I want there to be a gap inbetween the two.

Help would be really appreciated and don't worry if you don't know both, just post me one!

Thanks!

But you haven't describe what exactly problem do you have?

First one is spawning.

Spawning an object you can do by System -> Create object or by some sprite object -> spawn object.

I need to spawn a car at random 1-3 seconds...

You can use "Every x second" or any other loop with "wait" function, but there is a special way you have to build a delay between iterations. You can learn it here: https://www.scirra.com/tutorials/723/using-wait-in-loops.

Regarding random function, the most precise is the following format: "floor(random(b-a+1)) + a" which returns an integer number from "a" to "b" (including them).

and also spawn different types of cars (as I have different coloured cars and I don't want them to be the same).

If the only thing which differs is the color then I encourage to use one sprite and put various cars as separate frames.

Second thing is stopping. once the first car is stopped, the car behind goes ontop. I know I could put collide but I want there to be a gap inbetween the two.

Well this really depends on how exactly your game works. You can for instance check the distance between car1 and car2 by X and Y position.